Add OpenAI tool calling support

internal/providers/openai/openai.go

@@ -91,6 +91,8 @@ func (p *Provider) Generate(ctx context.Context, messages []api.Message, req *ap
 			oaiMessages = append(oaiMessages, openai.SystemMessage(content))
 		case "developer":
 			oaiMessages = append(oaiMessages, openai.SystemMessage(content))
+		case "tool":
+			oaiMessages = append(oaiMessages, openai.ToolMessage(content, msg.CallID))
 		}
 	}
 
@@ -108,6 +110,29 @@ func (p *Provider) Generate(ctx context.Context, messages []api.Message, req *ap
 		params.TopP = openai.Float(*req.TopP)
 	}
 
+	// Add tools if present
+	if req.Tools != nil && len(req.Tools) > 0 {
+		tools, err := parseTools(req)
+		if err != nil {
+			return nil, fmt.Errorf("parse tools: %w", err)
+		}
+		params.Tools = tools
+	}
+
+	// Add tool_choice if present
+	if req.ToolChoice != nil && len(req.ToolChoice) > 0 {
+		toolChoice, err := parseToolChoice(req)
+		if err != nil {
+			return nil, fmt.Errorf("parse tool_choice: %w", err)
+		}
+		params.ToolChoice = toolChoice
+	}
+
+	// Add parallel_tool_calls if specified
+	if req.ParallelToolCalls != nil {
+		params.ParallelToolCalls = openai.Bool(*req.ParallelToolCalls)
+	}
+
 	// Call OpenAI API
 	resp, err := p.client.Chat.Completions.New(ctx, params)
 	if err != nil {
@@ -115,14 +140,20 @@ func (p *Provider) Generate(ctx context.Context, messages []api.Message, req *ap
 	}
 
 	var combinedText string
+	var toolCalls []api.ToolCall
+
 	for _, choice := range resp.Choices {
 		combinedText += choice.Message.Content
+		if len(choice.Message.ToolCalls) > 0 {
+			toolCalls = append(toolCalls, extractToolCalls(choice.Message)...)
+		}
 	}
 
 	return &api.ProviderResult{
-		ID:    resp.ID,
-		Model: resp.Model,
-		Text:  combinedText,
+		ID:        resp.ID,
+		Model:     resp.Model,
+		Text:      combinedText,
+		ToolCalls: toolCalls,
 		Usage: api.Usage{
 			InputTokens:  int(resp.Usage.PromptTokens),
 			OutputTokens: int(resp.Usage.CompletionTokens),
@@ -168,6 +199,8 @@ func (p *Provider) GenerateStream(ctx context.Context, messages []api.Message, r
 				oaiMessages = append(oaiMessages, openai.SystemMessage(content))
 			case "developer":
 				oaiMessages = append(oaiMessages, openai.SystemMessage(content))
+			case "tool":
+				oaiMessages = append(oaiMessages, openai.ToolMessage(content, msg.CallID))
 			}
 		}
 
@@ -185,6 +218,31 @@ func (p *Provider) GenerateStream(ctx context.Context, messages []api.Message, r
 			params.TopP = openai.Float(*req.TopP)
 		}
 
+		// Add tools if present
+		if req.Tools != nil && len(req.Tools) > 0 {
+			tools, err := parseTools(req)
+			if err != nil {
+				errChan <- fmt.Errorf("parse tools: %w", err)
+				return
+			}
+			params.Tools = tools
+		}
+
+		// Add tool_choice if present
+		if req.ToolChoice != nil && len(req.ToolChoice) > 0 {
+			toolChoice, err := parseToolChoice(req)
+			if err != nil {
+				errChan <- fmt.Errorf("parse tool_choice: %w", err)
+				return
+			}
+			params.ToolChoice = toolChoice
+		}
+
+		// Add parallel_tool_calls if specified
+		if req.ParallelToolCalls != nil {
+			params.ParallelToolCalls = openai.Bool(*req.ParallelToolCalls)
+		}
+
 		// Create streaming request
 		stream := p.client.Chat.Completions.NewStreaming(ctx, params)
 
@@ -193,19 +251,35 @@ func (p *Provider) GenerateStream(ctx context.Context, messages []api.Message, r
 			chunk := stream.Current()
 
 			for _, choice := range chunk.Choices {
-				if choice.Delta.Content == "" {
-					continue
+				// Handle text content
+				if choice.Delta.Content != "" {
+					select {
+					case deltaChan <- &api.ProviderStreamDelta{
+						ID:    chunk.ID,
+						Model: chunk.Model,
+						Text:  choice.Delta.Content,
+					}:
+					case <-ctx.Done():
+						errChan <- ctx.Err()
+						return
+					}
 				}
 
-				select {
-				case deltaChan <- &api.ProviderStreamDelta{
-					ID:    chunk.ID,
-					Model: chunk.Model,
-					Text:  choice.Delta.Content,
-				}:
-				case <-ctx.Done():
-					errChan <- ctx.Err()
-					return
+				// Handle tool call deltas
+				if len(choice.Delta.ToolCalls) > 0 {
+					delta := extractToolCallDelta(choice)
+					if delta != nil {
+						select {
+						case deltaChan <- &api.ProviderStreamDelta{
+							ID:            chunk.ID,
+							Model:         chunk.Model,
+							ToolCallDelta: delta,
+						}:
+						case <-ctx.Done():
+							errChan <- ctx.Err()
+							return
+						}
+					}
 				}
 			}
 		}